1. Field of the Invention
The present invention relates to rasps. More particularly, the present invention relates to rasps for preparing bones of various patients to receive a prosthetic implant and to a method for using the same.
2. Description of the Related Art
Joint arthroplasty is a surgical procedure for replacing damaged components of a joint with prosthetic components. Such damage may be caused by, for example, traumatic injury or some form of arthritis, such as osteoarthritis. Joint arthroplasty may relieve pain and restore motion in the damaged joint.
The hip joint is formed between the head of the femur and the acetabulum of the pelvis. Therefore, arthroplasty of the hip joint can involve replacing the femoral head and/or the acetabulum with prosthetic implants. Replacing the femoral head, in particular, involves resecting the femoral head along its neck and preparing the intramedullary canal of the femur to receive a prosthetic femoral hip stem. This prosthetic femoral hip stem will ultimately anchor a prosthetic femoral head.
Preparation of the intramedullary canal has a significant impact on the entire arthroplasty procedure. The prepared canal determines the fit between the prosthetic femoral hip stem and the femur, which in turn determines the fit between the prosthetic femoral head and the acetabulum. For example, if the prepared canal is too large, gaps may form between the prosthetic femoral hip stem and the femur, which could cause shifting or rotation of the hip stem. Also, if the prepared canal is too large, the prosthetic femoral hip stem may be seated too deep within the femur, resulting in an unnatural placement of the prosthetic femoral head. On the other hand, if the prepared canal is too small, the prosthetic femoral hip stem may not be seated deep enough within the femur, also resulting in an unnatural placement of the prosthetic femoral head.
Currently, surgeons have available in the operating room a single rasp to prepare the intramedullary canals of each and every patient. This single rasp corresponds to the size and shape of the prosthetic femoral hip stem to be implanted. However, each patient has unique bone characteristics, depending on, for instance, age, health, and gender. Typically, a younger male will have harder, more dense bone than an older female. Therefore, the exact same rasp may result in differently sized canals, depending on the patient's unique bone characteristics. More specifically, the rasp may produce a canal that is too small in a patient with hard, dense bone, while the rasp may produce a canal that is too large in a patient with soft, weak bone.